Let's rewrite the given expression:

18x⁻¹

Step 1: Rewrite with Positive Exponents

To eliminate the negative exponent, recall that:

$x^{-1} = \frac{1}{x}$

Thus,

$18x^{-1} = \frac{18}{x}$

Step 2: Check for Simplification

Since there's nothing else to factor or reduce, this is the simplest form.

Final Answer:

• Choice A: The expression $18x^{-1}$ expressed using positive exponents is $\frac{18}{x}$. This cannot be simplified further.

Would you like any further explanation on exponents or simplification steps?

Here are 5 related questions you might find useful:

1. How do you simplify expressions with multiple negative exponents?
2. What is the rule for multiplying terms with exponents?
3. How do you simplify fractions with exponents in both the numerator and denominator?
4. What happens when you raise a power to another power?
5. How do you handle expressions with both negative and fractional exponents?

Tip: When dealing with negative exponents, remember they represent reciprocals!